Tea is a shrub, grown for a hot drink made from its leaves. Tea is appreciated both for its stimulant properties and health benefits, and as the centre of social rituals such as the Japanese tea ceremony and British teatime.

Tea is a beverage made by steeping processed leaves, buds, or twigs of the tea bush (Camellia sinensis) in hot water for a few minutes. The processing can include oxidation (fermentation), heating, drying, and the addition of other herbs, flowers, spices, and fruits. There are four basic types of true tea: black tea, oolong tea, green tea, and white tea. The term "herbal tea" usually refers to infusions of fruit or herbs (such as rosehip, chamomile, or jiaogulan) that contain no C. sinensis. (Alternative terms for herbal tea that avoid the word "tea" are tisane and herbal infusion). This article is concerned exclusively with preparations and uses of the tea plant C. sinensis. Tea is a natural source of caffeine, theobromine, theophylline, theanine, and antioxidants, but it has almost no fat, carbohydrates, or protein. It has a cooling, slightly bitter and astringent taste.

Processing and classification

The types of tea are distinguished by their processing. Leaves of Camellia sinensis, if not dried quickly after picking, soon begin to wilt and oxidize. The leaves turn progressively darker, as chlorophyll breaks down and tannins are released. The next step in processing is to stop the oxidation process at a predetermined stage by deactivating the enzymes responsible by heating, which in black tea is done simultaneously with drying. The term fermentation is still used in tea process to describe this process, even though no true fermentation happens (i.e., the process is not driven by microorganisms). Without careful moisture and temperature control, however, fungi will grow on tea. The fungi cause real fermentation which will contaminate the tea with toxic and sometimes carcinogenic substances as well as off-flavours, so that the tea must be discarded. Tea is traditionally classified based on the degree or period of "fermentation" (actually enzymatic oxidation) the leaves have undergone: White tea Young leaves (new growth buds) that have undergone no oxidation; the buds may be shielded from sunlight to prevent formation of chlorophyll. White tea is produced in lesser quantities than most of the other styles, and can be correspondingly more expensive than tea from the same plant processed by other methods. It is also less well-known in countries outside of China, though this is changing with increased western interest in organic or premium teas. Green tea The oxidation process is stopped after a minimal amount of oxidation by application of heat; either with steam, a traditional Japanese method; or by dry cooking in hot pans, the traditional Chinese method. Tea leaves may be left to dry as separate leaves or rolled into small pellets to make gun-powder tea. The latter process is time-consuming and is typically done only with pekoes of higher quality. The tea is processed within one to two days of harvesting. Oolong Oxidation is stopped somewhere between the standards for green tea and black tea. The oxidation process will take two to three days. In Chinese, semi-oxidized teas the are collectively grouped as blue tea (青茶, literally: blue-green tea), while the term "oolong" is used specifically as names for certain semi-oxidized teas[4] Black tea/Red tea The tea leaves are allowed to completely oxidize. Black tea is the most common form of tea in southern Asia (India, Pakistan, Bangladesh, Sri Lanka, etc.) and in the last century many African countries including Kenya, Burundi, Rwanda, Malawi and Zimbabwe. The literal translation of the Chinese word is red tea, which may be used by some tea-lovers. The Chinese call it red tea because the actual tea liquid is red. Westerners call it black tea because the tea leaves used to brew it are usually black. However, red tea may also refer to rooibos, an increasingly popular South African tisane. The oxidation process will take around two weeks and up to one month. Black tea is further classified as either orthodox or CTC (Crush, Tear, Curl, a production method developed about 1932). Unblended black teas are also identified by the estate they come from, their year and the flush (first, second or autumn). Orthodox and CTC teas are further graded according to the post-production leaf quality by the Orange Pekoe system. Pu-erh (also known as Póu léi (Polee) in Cantonese), Two forms of pu-erh teas are available, "raw" and "ripened". "Raw" or "green" pu-erh may be consumed young or aged to further mature. During the aging process, the tea undergoes a second, microbial fermentation. "Ripened" pu-erh is made from green pu-erh leaf that has been artificially oxidized to approximate the flavour of the natural aging process. This is done through a controlled process similar to composting, where both the moisture and temperature of the tea are carefully monitored. Both types of pu-erh tea are usually compressed into various shapes including bricks, discs, bowls, or mushrooms. While most teas are consumed within a year of production, pu-erh can be aged for many years to improve its flavour, up to 30 to 50 years for raw pu-erh and 10 to 15 years for ripened pu-erh, although experts and aficionados disagree about what the optimal age is to stop the aging process. Most often, pu-erh is steeped for up to five minutes in boiling water. Additionally, some Tibetans use pu-erh as a caloric food, boiled with yak butter, sugar and salt to make yak butter tea. Teas that undergo a second oxidation, such as pu-erh and liu bao, are collectively referred to as black tea in Chinese. This is not to be confused with the English term Black tea, which is known in Chinese as red tea. Yellow tea Either used as a name of high-quality tea served at the Imperial court, or of special tea processed similarly to green tea, but with a slower drying phase. Kukicha Also called winter tea, kukicha is made from twigs and old leaves pruned from the tea plant during its dormant season and dry-roasted over a fire. It is popular as a health food in Japan and in macrobiotic diets. Genmaicha Literally "brown rice tea" in Japanese, a green tea blended with dry-roasted brown rice (sometimes including popped rice), very popular in Japan but also drunk in China. Flower tea Teas processed or brewed with flowers; typically, each flower goes with a specific category of tea, such as green or red tea. The most famous flower tea is jasmine tea (hua chá, literally "flower tea", in Mandarin; h­eung pín in Cantonese), a green or oolong tea scented (or brewed) with jasmine flowers. Chrysanthemum, osmanthus, lotus, rose, and lychee are also popular flowers. Faux Tea Fake tea is made by unscrupulous traders. It is made using bitter tasting plants or recycled tea leaf. The colour and taste of the final product comes from an artificial additive.